Disk set
The present invention relates to a kind of glass or ceramic disk set of utilizing, more specifically to a kind of disk set that can significantly reduce from the crosstalk noise of magnetic head in the device as disk base material.
Generally all use aluminium as magnetic disc substrate traditionally.Recently, in the hard disk assembly field, high capacity and miniaturization are desirable.Obtaining one of jumbo method just is to use glass or pottery as magnetic disc substrate.When using this magnetic base,, therefore promoted recording density because its good advantage such as character of surface can obtain lower head gimbal amount at an easy rate.
In the traditional disk set that uses aluminum matrix, a pair of electromagnetic coupled between the magnetic head up and down is worn-out owing to the aluminium base disk of placing therebetween can obtain screen, but under the situation of glass as magnetic disc substrate, the above-mentioned electromagnetic coupled between the magnetic head up and down can not be worn-out by screen, crosstalk noise strengthens as a result, the problem of Signal Degrade when having produced signal regeneration.For example, from using the disk of thick glass of 1.27mm and aluminium base respectively, by 4MH of head records of lower surface
ZSignal, again by measuring crosstalk noise in the regeneration of the magnetic head of upper surface, through measuring (4MH
8Output level) the back crosstalk noise of finding the glass substrate disk than the crosstalk noise of aluminium base disk big+8.9dB.Under glass substrate disk situation, the decay of regenerated signal is defined as
f' 4M/
f4M, crosstalk noise is
f' 1.5M/
f' 4M is right
f4M '
f' 4M reaches
f' 1.5M measures.So obtain pad value and crosstalk noise value to be respectively-1.73dB and-46.4dB.For the aluminium base disk, with the method measurement same with the glass substrate disk
f4M,
f' 4M and
f' 1.5M, then pad value and crosstalk noise be respectively-0.38dB and-60.6dB.Clearly for the glass substrate disk, signal subtracts with crosstalk noise all very big.
f4M is the 4MH that lower surface magnetic head executive logging is regenerated by the upper surface magnetic head before
ZSignal level.
f' 4M writes down the 4MH of back by the regeneration of upper surface magnetic head for the lower surface magnetic head
ZSignal level.
f' 1.5M is the 1.5MH that is regenerated by the top magnetic head behind the magnetic head executive logging of bottom
ZSignal level.
The magnetic characteristic of the recording layer of the disk that uses in experiment is as follows:
For aluminium base, H
c=1 * 10
3Oe, M
T ≌ 4.2 * 10
-3Em
/ cm
2For the glass-based disk, Hc ≌ 1.25 * 10
3Oe.M γ t ≌ 4.0 * 10
3Emu/cm
3
The gap length of employed magnetic head is 0.6 μ m, and track width is Tw ≌ 10 μ m.In this example, the head gimbal amount is 8 μ.As mentioned above, when using aluminium substrate disk, the electromagnetic coupled of magnetic head can be worn-out by the aluminium base screen up and down, so crosstalk noise does not constitute serious problem.
And for the disk set that uses glass substrate, crosstalk noise then constitutes a serious problem, as mentioned above, because the coupling up and down between the magnetic head can not we falls by screen.
For the disk set of aforesaid traditional use glass substrate disk, exist the problem of the crosstalk noise that produces because of a pair of electromagnetic coupled between the magnetic head up and down that is arranged on the disk both sides.
Purpose of the present invention is exactly only to move the position of a pair of magnetic head up and down and needn't form shielding layer on magnetic disc substrate and reach crosstalking of the above-mentioned electromagnetic signal of reduction, obtains a kind of disk set that can reduce crosstalk noise and signal output attenuatoin.
Disk set of the present invention is like this design, and a pair of upper and lower magnetic head assembly of the both sides of glass substrate is arranged on the position of staggering.
According to the present invention, by a pair of location arrangements of magnetic head to stagger up and down with the glass substrate both sides, the decay of crosstalk noise and signal output is lowered.
Fig. 1 has shown the magnetic head seen from the sense of rotation of disk according to embodiments of the invention and the position relation of disk;
Fig. 2 is the one-piece construction figure of disk set of the present invention;
Fig. 3 is the structural drawing of magnetic actuator;
Fig. 4 is the decay that shows the signal output that obtains from method and the present invention of prior art and the table of crosstalk noise value.
1 ... disk, 2a ... first magnetic head, 2b ... second magnetic head, 3a ... first slide block, 3b ... second slide block, 6 ... pedestal, 8 actuators, 9 ... coil, 10 ... yoke, 11 ... permanent magnet.
Before the embodiment that describes Fig. 1, at first contrast the one-piece construction that Fig. 2 and Fig. 3 describe disk set of the present invention.Disk set comprises pedestal 6 and loam cake 7.On pedestal 6, actuator 8 is installed by axle 12, on actuator 8, be equipped be in each above the disk and below slide block 3a and 3b.With respect to the offside of axle 12 coil 9 is installed at actuator 8.On coil 9, last yoke 10a is fixed on the pedestal 6 and 9 one on off-line circle gives fixed gap.Under coil 9, lower yoke 10b is fixed on that off-line circle 9 has one to give fixed gap on the pedestal 6.A side fixed permanent magnet 11a and the 11b of yoke 10a and lower yoke 10b in the face of coil 9.Coil 9 and permanent magnet 11a and 11b constitute voice coil motor, and it produces a power by feeding electric current in the coil in the magnetic field that produces at permanent magnet, make actuator 8 motions, and the direction of motion of actuator 8 is by the current conditions decision of flowing through coil 9.
Referring now to Fig. 1 embodiments of the invention are described.The substrate of disk 1 is made by glass, by evaporation deposition magnetic coating is arranged in the upper and lower surface of substrate.At the upper surface of disk 1, the first magnetic head 2a is positioned.The first magnetic head 2a is supported by the first slide block 3a.The record of the data of the magnetic medium layer of the upper surface of disk 1 and regeneration by in the coil of the first magnetic head 2a by carrying out from the drive current of driving circuit (not shown).Similarly, at the lower surface of disk 1, the second magnetic head 2b is positioned and is supported by the 2nd slide block 3b.Data recording on the magnetic interlayer on the disk 1 and regeneration are by carrying out by the drive current from above-mentioned driving circuit in the coil of the second magnetic head 2b.
The first magnetic head 2a and the second magnetic head 2b are with recording track location that to depart from a value be d.These magnetic heads all are the monolithic heads that strikes up partnership with slide block.
Referring to Fig. 1, at first by the first magnetic head 2a 4MH of upper surface record at disk 1
ZSignal is then by second magnetic head 2b 1.5MH of lower surface record at disk 1
ZSignal.Above-described
f4M(is before the second magnetic head 2b tracer signal, by the 4MH of first magnetic head 2a generation
ZThe regenerated signal level),
f' 4M(is after the lower surface tracer signal of the second magnetic head 2b at disk 1, by the 4MH of first magnetic head generation
ZThe regenerated signal level), reach
f' 1.5M(is after the lower surface tracer signal of the second magnetic head 2b at disk 1,1.5MHZ regenerated signal level by first magnetic head 2a generation) can before and after the second magnetic head 2b tracer signal, be measured respectively, according to the value that obtains, calculate the decay and the crosstalk noise of the described regenerated signal in front more separately.
Now above-mentioned signal attenuation and crosstalk noise determined, when the first magnetic head 2a and the second magnetic head 2b are disposed in that same recording track (d=0) goes up and comparing result when quantity is arranged between two magnetic heads is the skew of d=70 is seen table among Fig. 4 on recording track.
From Fig. 4, can obviously see, the first magnetic head 2a and the second magnetic head 2b relatively depart from out mutually giving on the recording track position of quantitative d, as shown in Figure 1, then the decay of regenerated signal and crosstalk noise all obviously reduce, respectively from-1.73dB to-0.29dB and from-46.4dB to-54.6dB.The magnetic characteristic of the recording layer of the thickness of the substrate of employed disk and disk and characteristic of magnetic head or the like are all with above-mentioned identical in this experiment.
Certainly, by relative position, also can reduce the decay and the crosstalk noise of the regenerated signal of the foregoing description description at magnetic head sense of rotation displacement magnetic gap.But make first magnetic head and second magnetic head relatively depart from some magnetic tracks mutually and arrange the decay that can more effectively reduce crosstalk noise and replay signal.
The foregoing description is made substrate with glass, but is to use pottery also can obtain the similar effects of the foregoing description.
In addition, use in the above-described embodiments be monolithic head as magnetic head, but be to use thin-film head or combined record also can obtain the effect that the foregoing description reaches.
In addition, if substrate thickness reduces, the coercive force of magnetic medium (HC) reduces, and the suspension of magnetic head also reduces.Effect of the present invention can be strengthened to identical degree.
Just as described like that, the present invention only by change be placed on the disk both sides magnetic head up and down relative position and needn't on magnetic disc substrate, form shielding layer and obtain the significantly reduced effect of the decay that makes crosstalk noise and output signal at lower cost.